1.528 F SI1: https://www.briangavindiamonds.com/diamonds/diamond-details/1.528-f-si1-round-diamond-ags-104095011008#!prettyPhoto[gallery2]/3/
1.543 D SI1: Pictures attached below. $1,500 less.
The 1.528 looks better cut but is it really THAT difference enough to justify costing an extra $1,500... when you compare it to this other really well-cut diamond that is slightly larger AND that's also a D in color?!?!!?
Diamond experts which would you pick and why?! Both have similar upgrade policies and return policies.
The biggest flashes of scintillation the diamond being, eye clean, and no yellow tint are the most important factors for us. The extra $1,500 doesn't push our budget to an uncomfortable place.
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It does seem a tad high on price. I would try to at least negotiate getting it set for free if not more. Whiteflash only charges 100 for setting the stone. Also, ask for an ideal scope image at the least just to evaluate light potential leakages. If it's 3x its at least a pretty decent cut so you don't need to worry as much about symmetry.

Ask them what they mean by eye clean. Some vendors use that term loosely, where others have told me they define it as no visible inclusion from a person with 20/20 vision from as close as 10 inches away.

Thanks again @davidelevi
I ended up purchasing the 1.528, F after Brian himself and others made it clear that the only way to spot the inclusions, no matter how close you are.... Is with a scope, OR unless if you look at the diamond upside down. I can't wait to see what it looks like in person!
Now I just need to figure out who I can trust to properly set the stone. I live in a small city with low-end jewelry stores. Should I ship the loose stone to the place that I'm purchasing the setting from? Or should I ship the setting and loose stone back to Brian Gavin and have them set it for me.
I'm probably getting the setting from Whiteflash or Solomon Brothers.

@davidelevi So you think they have a good possibility of being eye clean in even abnormal viewing conditions? From what I've read, normal viewing conditions is 10-12 inches away from a person with 20/20 vision. We both have 20/20 vision and I'm just worried that if she looks at it even closer than the 10-12 inch standard she might be able to spot something, even though they all appear to be white inclusions. Would you recommend giving these a diamonds a shot under that kind of scrutiny? I love everything else about these two diamonds, it's just these damn inclusions that are holding me back.
I really appreciate your insight on this David, Thanks again.

Thank you for the responses. @Furqan Shafi I'll be sure to ask Brian Gavin or someone from their staff the same question, hopefully they are honest. And @davideleviYou brought up a great point about it being mind-clean. However, I think it's just visual thing, and that she just wants the inclusions to be invisible unless you're looking through a scope.. Is that possible with SI1's? Especially these two in particular... or is it 100% necessary to go up to VS2 or VS1 to achieve that?

Which diamond has the least noticeable inclusions? Making sure the diamond is eye clean from like like 2 inches is what's most important to her as long as it's G or above color. Which would you pick and why?
https://www.briangavindiamonds.com/diamonds/diamond-details/1.514-g-si1-round-diamond-ags-104095011009#!prettyPhoto[gallery2]/0/
https://www.briangavindiamonds.com/diamonds/diamond-details/1.528-f-si1-round-diamond-ags-104095011008
Which do you think has the better Ideal-Scope / ASET images?
Any advice is welcomed, and thank you!